Trusted execution environments: What, how and why?

What is a TEE?

The trusted execution environment, or TEE, is an isolated area on the main processor of a device that is separate from the main operating system. It ensures that data is stored, processed and protected in a trusted environment. TEE provides protection for any connected “thing” by enabling end-to-end security, protected execution of authenticated code, confidentiality, authenticity, privacy, system integrity and data access rights.

It is already used widely in complex devices, such as smartphones, tablets and set-top boxes, and also by manufacturers of constrained chipsets and IoT devices in sectors such as industrial automation, automotive and healthcare, who are now recognizing its value in protecting connected things.

How does it work?

The fundamental concepts of a TEE are trust, security and isolation of sensitive data. The most advanced TEE implementations embed devices with unique identities via Roots of Trust. These enable key stakeholders in the value chain to identify whether the device they’re interacting with is authentic. It also cryptographically protects both data and applications stored inside it. Applications that sit within the TEE are known as trusted applications. The data stored on and processed by trusted applications is protected and interactions made (whether between applications or the device and end user) are securely executed.

This is because a TEE enables:

• Secure peripheral access — It has the unique capability of being able to directly access and secure peripherals such as the touchscreen or display (i.e., the user interface), offering protection for fingerprint sensors, cameras, microphones, speakers and so on.
• Secure communication with remote entities — It can secure data, communications and cryptographic operations. Encryption keys are only stored, managed and used within the secure environment, with no opportunity for eavesdropping. This is particularly relevant for IoT as secure cloud enrollment of things like sensors is central to scalability.
• Trusted device identity and authentication — Some TEEs inject a root of trust that enables the legitimacy of the device to be verified by the connected service which it is trying to enroll with.

Why should we care?

Our world is driven by data and we need to get better at protecting it
TEE technology solves a significant problem for anyone concerned about protecting data. Take manufacturers and service providers for example; the TEE is increasingly playing a central role in preventing high-profile hacking, data breaches and use of malware, all of which can result in significant brand damage.

As devices become more complex so do their security requirements
It is clear that a smart heart rate monitor or insulin pump will not have the same capabilities as a connected car. Nevertheless, they all embed critical software and handle highly sensitive data and functions that are crucial to protect.

But it is not just the data that is key — secure connectivity and communication are also fundamental. Smart devices increasingly rely on connectivity to function (whether to pair with other devices or enroll with cloud services). This, however, makes them highly vulnerable. The TEE tackles this problem by allowing a trusted application to securely share secrets with a remote entity, such as a server or a secure element, in order to establish a secure communication channel.

IoT needs trust and scalability
The IoT value proposition is very desirable — cost savings, new/faster/better services, increased revenue, improved operational efficiency, enhanced digital lives. The IoT landscape is a diverse and ever-expanding space of possibility — and some of the best benefits haven’t even been imagined yet!

To fully take advantage of the current and future benefits that IoT offers, devices need to be scalable. This can only be achieved if their underlying technology is built on a foundation of security that can provide robust protection long into the future.

The TEE enables scalability in IoT by embedding hardware-backed protection at the heart of the device. New technologies, like Digital Holograms, are also coming forward to solve problems like device attestation, protection from overproduction, cloning and tampering, supply chain integrity from start to in-field operation, and trusted, autonomous cloud enrollment.

What next?

The trusted execution environment is already bringing value to a range of device types and sectors, which we’ll explore in greater detail in upcoming blogs. What’s really exciting though, is not the technology itself, but the options and possibilities it opens up. Whether it’s for developers to add additional value to their services by utilizing the hardware isolation, or the complementary technologies like Digital Holograms that sit alongside to add value for service providers and device makers, this is a technology that is only just gaining momentum. For example, our open TEE is already embedded into more than 1.5 billion devices worldwide, a number that has grown by more than 50% in less than a year, and as the IoT ecosystem and its security requirements expand even further, we can expect that growth rate to continue to rise.

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